Work holder for holding electrical connectors during insertion of terminals into cavities in the connector comprises a positioning fixture and a clamping member. The connector is clamped between one face of the positioning fixture and the clamping member. The positioning fixture has terminal guiding openings extending therethrough and has aligning and guiding surface portions which guide the connector towards these openings when the connector is being clamped in the fixture so that the cavities in the connector are in precise alignment with the terminal guiding openings. The fixture is intended for use in a robot and permits reorientation of the connector, from right to left, so that connectors requiring terminals in two different orientations can be accommodated.